The invention belongs to the technical field of engine emission, and discloses a
diesel engine DPF
trapping efficiency fault diagnosis method. The
diesel engine DPF
trapping efficiency fault diagnosis method comprises the following steps: S1, DPF
pressure difference measurement values under different working conditions are acquired, and corresponding engine
exhaust gas volume flow, DPF carrier average temperature and DPF carbon load are obtained; S2, a DPF real-
time pressure difference value calculation model is established, and a DPF real-
time pressure difference value is calculated; S3, a fault diagnosis enabling area is calibrated according to the working condition information; and S4, a
differential pressure deviation value between the DPF
differential pressure measurement value and the DPF real-time
differential pressure value is calculated, the differential pressure deviation value is compared with a differential pressure deviation threshold value, and when the differential pressure deviation value is not greater than the differential pressure deviation threshold value, it is judged that the
trapping efficiency is normal, otherwise, it is judged that a fault exists. According to the
diesel engine DPF trapping efficiency fault diagnosis method, the DPF trapping efficiency fault is diagnosed through the mathematical calculation model of the DPF real-
time pressure difference value, the method is simple and accurate, a PM sensor is not used, and the cost is greatly reduced.